1. Field of the Invention
The present invention relates to a glass melting furnace for melting constituent materials of glass into molten glass of good quality which will be supplied to a feeder or the like, and more particularly to a drainage mechanism of such a glass melting furnace.
2. Description of the Relevant Art
Glass melting furnaces for melting ingredient materials of glass are generally constructed of refractory bricks. While the molten glass and the refractory bricks are being heated to high temperature in the glass melting furnace, materials of the refractory bricks inevitably melt into the molten glass.
The molten glass which is rendered heterogeneous by the addition of refractory brick materials has a larger specific gravity and a higher viscosity than those of normal molten glass free of refractory brick materials, and also has different characteristics such as a refractive index. If the amount of heterogeneous molten glass is increased, it remains on the bottom of the melting furnace and tends to flow into a feeder or the like which supplies molten glass to a glass shaping mechanism or the like that is located next to the melting furnace.
FIGS. 5 and 6 of the accompanying drawings illustrate conventional glass melting furnaces designed for solving the above problem.
The glass melting furnace shown in FIG. 5 comprises a furnace body 100 for containing molten glass G, a throat 101 extending horizontally from the furnace body 100 and spaced upwardly from the bottom of the furnace body 100, and a feeder (not shown) connected to the throat 101. The bottom of the furnace body 100 has a vertical drain hole 102 defined therethrough for draining out heterogeneous molten glass 103 collected on the bottom of the furnace body 100.
The glass melting furnance of FIG. 6 has a throat 101 lying at the same level as the bottom of a furnace body 100, and a dam 104 disposed on the bottom of the furnace body 100 in front of the inlet of the throat 101. Heterogenous molten glass 103 is drained out of a drain hole 102 defined vertically in the bottom of the furnace body 100.
The heterogeneous molten glass 103 has a greater specific gravity and a higher viscosity than those of normal molten glass. Therefore, when draining out the heterogenenous molten glass from the drain holes as shown in FIGS. 5 and 6, there is a tendency for normal molten glass to flow centrally through the flow of heterogenenous molten glass as indicated in FIG. 7.
More specifically, the molten glass G in the furnace tends to move toward the throat 101, i.e., in a lateral direction F, and so does the heterogeneous molten glass 103. Since the heterogenous molten glass 103 is highly viscous and hence less flowable, it is less liable to flow out of the drain hole 102 due to the lateral force applied in the direction F unless it flows near the drain hole 102. The normal homogeneous molten glass is low in viscosity and more flowable, it can easily flow through the drain hole 102 while being mixed in the stream of the heterogeneous molten glass 103 through the drain hole 102. As a result, the heterogeneous molten glass 103 cannot fully be drained out, but remains to be accumulated on the bottom of the furnace body 100 up to a point where it will flow into the throat 101.